Measurement of viscoelastic constants and Poisson's ratio of carbon fiber reinforced composites using in-situ imaging

Dynamic Mechanical Analysis (DMA) is conducted to measure the viscoelastic nature of a material. The commercial DMA equipment calculates the complex modulus (E*) by assuming a constant Poisson's ratio. In this work, a method is developed for the simultaneous measurement of Poisson's ratio and complex modulus (E*) for carbon fiber (CF) reinforced Acrylonitrile Butadiene Styrene (ABS) composites using in-situ optical measurements and digital image correlation. The computation of E* includes shear deflection and relaxes the assumption of constant Poisson's ratio to obtain accurate values. DMA was conducted on 3D printed CF-ABS composite specimens with oscillating displacement of 10 mu m and static load of 1 N at 1 Hz loading frequency. The results in this work reveal that CF-ABS composite does not have a constant Poisson's ratio over temperature. Additionally, applying the Poisson's ratio correction results in higher values for the complex modulus. This work is beneficial for composites where the shear deflection component should not be neglected, and where variation of Poisson's ratio with respect to temperature is important.